Pfizer, Novo Nordisk Clash Over Metsera Acquisition

Pfizer is escalating its legal and regulatory battle with Novo Nordisk and Metsera, after the latter declared Novo Nordisk’s updated acquisition proposal superior to Pfizer’s existing merger agreement. The dispute underscores intensifying competition in the global market for obesity and cardiometabolic therapies.

Pfizer initially reached a definitive agreement in September 2025 to acquire Metsera, a clinical-stage biopharmaceutical company focused on obesity and cardiometabolic diseases, for about US$4.9 billion, reports MBN. Both companies’ Boards of Directors unanimously approved the deal, which was expected to close in the 4Q25, pending shareholder and regulatory approvals.

However, on Oct. 30, 2025, Metsera announced that its Board had determined a new, unsolicited proposal from Novo Nordisk constituted a “Superior Company Proposal” under the merger agreement with Pfizer. Novo Nordisk’s amended offer, valued at up to US$10 billion or US$86.20 per share, surpassed Pfizer’s revised offer of about US$8.1 billion.

In response,Pfizer accused Novo Nordisk of attempting to suppress competition by acquiring an emerging US challenger to protect its dominance in the glucagon-like peptide-1 (GLP-1) drug market. The company argued that Novo Nordisk’s proposal was structured to evade antitrust laws and carried significant regulatory risks. Pfizer stated its own proposal provided real, certain, and immediate value for Metsera shareholders and supported broader market competition.

Following Metsera’s decision, Pfizer filed lawsuits against Metsera, its Board, and Novo Nordisk. The complaints allege breach of contract, breach of fiduciary duty, and tortious interference in contract. Pfizer also claims Novo Nordisk’s actions amount to anticompetitive behavior intended to eliminate a potential rival before its collaboration with Pfizer could materialize.

Metsera rejected Pfizer’s accusations, stating it “disagrees with the allegations” and would defend its decisions in court. Novo Nordisk confirmed on Nov. 4 that its updated proposal was declared superior by Metsera’s Board and said the acquisition would enable it to enhance Metsera’s incretin and non-incretin analogue peptide programs.

On Nov. 5, the Delaware Court of Chancery denied Pfizer’s request for a temporary restraining order that would have prevented Metsera from terminating the merger agreement in favor of Novo Nordisk’s proposal. Pfizer said the decision did not address the underlying legal issues and vowed to continue its litigation efforts. The company maintained that Novo Nordisk’s “unprecedented and illegal scheme to circumvent antitrust scrutiny” would ultimately fail.

Metsera, in turn, expressed satisfaction with the court’s decision, saying it reaffirmed the Board’s ability to act in the best interests of shareholders. The company reiterated that Pfizer’s litigation claims were “nonsense” and that it would continue to prioritize shareholder and patient interests.